drm/amdgpu: only allow secure submission on rings which support that

Only GFX ring, SDMA ring and VCN decode ring support secure submission
at the moment.

Suggested-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Lang Yu <Lang.Yu@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>